6 files changed, 106 insertions, 75 deletions

diff --git a/dhall/src/imports.rs b/dhall/src/imports.rs
index ad0ae0f..d6da4d7 100644
--- a/dhall/src/imports.rs
+++ b/dhall/src/imports.rs
@@ -1,11 +1,89 @@
 // use dhall_core::{Expr, FilePrefix, Import, ImportLocation, ImportMode, X};
-use dhall_core::{Expr, StringLike, Import, X};
+use dhall_core::{Expr, Import, StringLike, X};
 // use std::path::Path;
-// use std::path::PathBuf;
+use dhall_core::*;
+use std::fmt;
+use std::fs::File;
+use std::io::Read;
+use std::path::Path;
+use std::path::PathBuf;
 
-pub fn resolve_imports<Label: StringLike, S: Clone>(
+pub fn panic_imports<Label: StringLike, S: Clone>(
     expr: &Expr<Label, S, Import>,
 ) -> Expr<Label, S, X> {
-    let no_import = |_: &Import| -> X { panic!("ahhh import") };
+    let no_import = |i: &Import| -> X { panic!("ahhh import: {:?}", i) };
     expr.map_embed(&no_import)
 }
+
+/// A root from which to resolve relative imports.
+#[derive(Debug, Clone, PartialEq, Eq)]
+pub enum ImportRoot {
+    LocalDir(PathBuf),
+}
+
+fn resolve_import(
+    import: &Import,
+    root: &ImportRoot,
+) -> Result<Expr<String, X, X>, DhallError> {
+    use self::ImportRoot::*;
+    use dhall_core::FilePrefix::*;
+    use dhall_core::ImportLocation::*;
+    let cwd = match root {
+        LocalDir(cwd) => cwd,
+    };
+    match &import.location {
+        Local(prefix, path) => {
+            let path = match prefix {
+                Parent => cwd.parent().unwrap().join(path),
+                _ => unimplemented!(),
+            };
+            load_dhall_file(&path, false)
+        }
+    }
+}
+
+#[derive(Debug)]
+pub enum DhallError {
+    ParseError(parser::ParseError),
+    IOError(std::io::Error),
+}
+impl From<parser::ParseError> for DhallError {
+    fn from(e: parser::ParseError) -> Self {
+        DhallError::ParseError(e)
+    }
+}
+impl From<std::io::Error> for DhallError {
+    fn from(e: std::io::Error) -> Self {
+        DhallError::IOError(e)
+    }
+}
+impl fmt::Display for DhallError {
+    fn fmt(&self, f: &mut fmt::Formatter) -> Result<(), fmt::Error> {
+        use self::DhallError::*;
+        match self {
+            ParseError(e) => e.fmt(f),
+            IOError(e) => e.fmt(f),
+        }
+    }
+}
+
+pub fn load_dhall_file(
+    f: &Path,
+    resolve_imports: bool,
+) -> Result<Expr<String, X, X>, DhallError> {
+    let mut buffer = String::new();
+    File::open(f)?.read_to_string(&mut buffer)?;
+    let expr = parser::parse_expr(&*buffer)?;
+    let expr = expr.take_ownership_of_labels();
+    let expr = if resolve_imports {
+        let root = ImportRoot::LocalDir(f.parent().unwrap().to_owned());
+        let resolve = |import: &Import| -> Expr<String, X, X> {
+            resolve_import(import, &root).unwrap()
+        };
+        let expr = expr.map_embed(&resolve).squash_embed();
+        expr
+    } else {
+        panic_imports(&expr)
+    };
+    Ok(expr)
+}
diff --git a/dhall/src/lib.rs b/dhall/src/lib.rs
index 95f7f6f..8add5b6 100644
--- a/dhall/src/lib.rs
+++ b/dhall/src/lib.rs
@@ -7,49 +7,4 @@ pub use crate::normalize::*;
 pub mod imports;
 pub mod typecheck;
 
-use dhall_core::*;
-use std::fmt;
-use std::fs::File;
-use std::io::Read;
-use std::path::Path;
-
-#[derive(Debug)]
-pub enum DhallError {
-    ParseError(parser::ParseError),
-    IOError(std::io::Error),
-}
-impl From<parser::ParseError> for DhallError {
-    fn from(e: parser::ParseError) -> Self {
-        DhallError::ParseError(e)
-    }
-}
-impl From<std::io::Error> for DhallError {
-    fn from(e: std::io::Error) -> Self {
-        DhallError::IOError(e)
-    }
-}
-impl fmt::Display for DhallError {
-    fn fmt(&self, f: &mut fmt::Formatter) -> Result<(), fmt::Error> {
-        use self::DhallError::*;
-        match self {
-            ParseError(e) => e.fmt(f),
-            IOError(e) => e.fmt(f),
-        }
-    }
-}
-
-/// `source_pool` is a Vec of strings to be used to store the contents of imported files.
-/// No ideal but necessary for lifetime reasons for now.
-pub fn load_dhall_file<'i, 'a: 'i>(
-    f: &Path,
-    source_pool: &'a mut Vec<String>,
-    _resolve_imports: bool,
-) -> Result<Expr<String, X, X>, DhallError> {
-    source_pool.push(String::new());
-    let mut buffer = source_pool.last_mut().unwrap();
-    File::open(f)?.read_to_string(&mut buffer)?;
-    let expr = parser::parse_expr(&*buffer)?;
-    let expr = expr.take_ownership_of_labels();
-    let expr = imports::resolve_imports(&expr);
-    Ok(expr)
-}
+pub use crate::imports::{load_dhall_file, DhallError};
diff --git a/dhall/src/main.rs b/dhall/src/main.rs
index 23c8108..d072fe7 100644
--- a/dhall/src/main.rs
+++ b/dhall/src/main.rs
@@ -65,7 +65,8 @@ fn main() {
         }
     };
 
-    let expr: Expr<String, _, _> = imports::resolve_imports(&expr.take_ownership_of_labels());
+    let expr: Expr<String, _, _> =
+        imports::panic_imports(&expr.take_ownership_of_labels());
 
     let type_expr = match typecheck::type_of(&expr) {
         Err(e) => {
diff --git a/dhall/tests/macros.rs b/dhall/tests/macros.rs
index 83510a3..5175238 100644
--- a/dhall/tests/macros.rs
+++ b/dhall/tests/macros.rs
@@ -41,7 +41,6 @@ macro_rules! make_spec_test {
         #[allow(unused_imports)]
         fn $name() {
             use crate::macros::*;
-            use dhall::imports::resolve_imports;
             use dhall::*;
             use dhall_core::*;
             use std::thread;
@@ -61,10 +60,7 @@ macro_rules! make_spec_test {
 }
 
 use dhall::*;
-use dhall_core::parser::*;
 use dhall_core::*;
-use std::fs::File;
-use std::io::Read;
 use std::path::PathBuf;
 
 pub enum Feature {
@@ -79,29 +75,23 @@ pub enum ExpectedResult {
 
 pub fn read_dhall_file<'i>(
     file_path: &str,
-    mut buffer: &'i mut String,
-) -> Result<Box<Expr<String, X, Import>>, ParseError> {
-    let mut file = File::open(&file_path).unwrap();
-    file.read_to_string(&mut buffer).unwrap();
-    let expr = parser::parse_expr(&*buffer)?;
-    Ok(Box::new(expr.take_ownership_of_labels()))
+) -> Result<Expr<String, X, X>, DhallError> {
+    load_dhall_file(&PathBuf::from(file_path), true)
 }
 
 pub fn run_test(base_path: &str, feature: Feature, expected: ExpectedResult) {
     use self::{ExpectedResult, Feature};
-    let mut source_pool = Vec::new();
     match (feature, expected) {
         (Feature::Parser, ExpectedResult::Success) => {
-            let file_path: PathBuf = (base_path.to_owned() + "A.dhall").into();
-            let _expr = load_dhall_file(&file_path, &mut source_pool, true)
+            let file_path = base_path.to_owned() + "A.dhall";
+            let _expr = read_dhall_file(&file_path)
                 .map_err(|e| println!("{}", e))
                 .unwrap();
             // panic!("{:?}", _expr);
         }
         (Feature::Parser, ExpectedResult::Failure) => {
-            let file_path: PathBuf = (base_path.to_owned() + ".dhall").into();
-            let err = load_dhall_file(&file_path, &mut source_pool, true)
-                .unwrap_err();
+            let file_path = base_path.to_owned() + ".dhall";
+            let err = read_dhall_file(&file_path).unwrap_err();
             match err {
                 DhallError::ParseError(_) => {}
                 e => panic!("Expected parse error, got: {:?}", e),
@@ -109,14 +99,9 @@ pub fn run_test(base_path: &str, feature: Feature, expected: ExpectedResult) {
         }
         (Feature::Normalization, ExpectedResult::Success) => {
             let expr_file_path = base_path.to_owned() + "A.dhall";
-            let mut expr_buffer = String::new();
-            let expr =
-                read_dhall_file(&expr_file_path, &mut expr_buffer).unwrap();
             let expected_file_path = base_path.to_owned() + "B.dhall";
-            let mut expected_buffer = String::new();
-            let expected =
-                read_dhall_file(&expected_file_path, &mut expected_buffer)
-                    .unwrap();
+            let expr = read_dhall_file(&expr_file_path).unwrap();
+            let expected = read_dhall_file(&expected_file_path).unwrap();
 
             assert_eq_!(
                 normalize::<_, _, X, _>(&expr),
diff --git a/dhall_core/src/core.rs b/dhall_core/src/core.rs
index 72389c5..3b98b39 100644
--- a/dhall_core/src/core.rs
+++ b/dhall_core/src/core.rs
@@ -376,6 +376,16 @@ impl<'i, S: Clone, A: Clone> Expr<&'i str, S, A> {
     }
 }
 
+impl<L: StringLike, S: Clone, A: Clone> Expr<L, S, Expr<L, S, A>> {
+    pub fn squash_embed(&self) -> Expr<L, S, A>
+    {
+        match self {
+            Expr::Embed(e) => e.clone(),
+            e => e.map_shallow(|e| e.squash_embed(), |x| x.clone(), |_| unreachable!(), |x| x.clone())
+        }
+    }
+}
+
 //  There is a one-to-one correspondence between the formatters in this section
 //  and the grammar in grammar.lalrpop.  Each formatter is named after the
 //  corresponding grammar rule and the relationship between formatters exactly matches
diff --git a/dhall_core/src/parser.rs b/dhall_core/src/parser.rs
index 9d0a88b..164d410 100644
--- a/dhall_core/src/parser.rs
+++ b/dhall_core/src/parser.rs
@@ -486,7 +486,9 @@ rule!(integer_literal_raw<core::Integer>;
     }
 );
 
-rule!(path<PathBuf>; captured_str!(s) => s.into());
+rule!(path<PathBuf>;
+    captured_str!(s) => (".".to_owned() + s).into()
+);
 
 rule!(parent_path<(FilePrefix, PathBuf)>;
     children!(p: path) => (FilePrefix::Parent, p)